Important is, that this function only checks for different elevation in pools of new vertices. If however a vertex is not changed and stays with old elevation and a new vertex at that position is created they could end up in dsf with different elevations.
Not clear if this ever happens.
In addition function "validate_mesh" does such elevation check before. So it should really not happen. However same checks are then partly done twice. Could be improved.
Important is, that this function only checks for different elevation in pools of new vertices. If however a vertex is not changed and stays with old elevation and a new vertex at that position is created they could end up in dsf with different elevations. Not clear if this ever happens. In addition function "validate_mesh" does such elevation check before. So it should really not happen. However same checks are then partly done twice. Could be improved.